package org.miniframework.inject;

import lombok.extern.slf4j.Slf4j;
import org.miniframework.core.BeanContainer;
import org.miniframework.inject.annotation.Autowired;
import org.miniframework.util.ClassUtil;
import org.miniframework.util.ValidationUtil;

import java.lang.reflect.Field;
import java.util.Set;

@Slf4j
public class DependencyInjector {

    /**
     * IOC容器
     */
    private BeanContainer beanContainer;

    public DependencyInjector(){
        beanContainer = BeanContainer.getInstance();
    }

    /**
     * 执行 IOC 注入
     */
    public void doIoc(){
        if (ValidationUtil.isEmpty(beanContainer.getClasses())){
            log.warn("empty classset in BeanContainer");
            return;
        }
        // 1. 遍历Beanr容器中所有class对象
        for (Class<?> clazz : beanContainer.getClasses()){
            // 2. 遍历class对象的所有成员变量
            Field[] fields = clazz.getDeclaredFields();
            if (ValidationUtil.isEmpty(fields)){
                continue;
            }
            for (Field field : fields){
                // 3. 找出被Autowired标记的成员变量
                if (field.isAnnotationPresent(Autowired.class)){
                    // 4. 获取这些成员变量的类型
                    Class<?> fieldClass = field.getType();
                    // 5. 获取这些成员变量的类型在容器里对应的实例
                    Autowired autowired = field.getAnnotation(Autowired.class);
                    String autowiredValue = autowired.value();
                    Object fieldValue = getFieldInstance(fieldClass,autowiredValue);
                    if (fieldValue == null){
                        throw new RuntimeException("unable to inject relevant type , target fieldClass is:" + fieldClass.getName() + " autowired to value" + autowiredValue);
                    }else{
                        // 6. 通过反射将对应的成员变量实例注入到成员变量所在类的实例里
                        Object targetBean = beanContainer.getBean(clazz);
                        ClassUtil.setField(field,targetBean,fieldValue,true);
                    }
                }
            }
        }
    }

    /**
     * 根据class在beanContainer里获取其实例或者实现类
     * @param fieldClass
     * @param autowiredValue
     * @return
     */
    private Object getFieldInstance(Class<?> fieldClass,String autowiredValue) {
        Object fieldValue = beanContainer.getBean(fieldClass);
        if (fieldValue != null){
            return fieldValue;
        }else {
            Class<?> implementedClass = getImplementClass(fieldClass,autowiredValue);
            if (implementedClass != null){
                return beanContainer.getBean(implementedClass);
            }else {
                return null;
            }
        }
    }

    /**
     * 获取接口实现类
     * @param fieldClass
     * @return
     */
    private Class<?> getImplementClass(Class<?> fieldClass,String autowiredValue) {
        Set<Class<?>> classSet = beanContainer.getClassesBySuper(fieldClass);
        if (!ValidationUtil.isEmpty(classSet)){
            if (ValidationUtil.isEmpty(autowiredValue)){
                if (classSet.size() == 1){
                    return classSet.iterator().next();
                }else{
                    // 多个实现类，未指定类型，抛出异常
                    throw new RuntimeException("multiple implemented classes for "+fieldClass.getName() + " please @Autowired's value to pick one");
                }
            }else{
                for (Class<?> clazz : classSet){
                    if (autowiredValue.equals(clazz.getSimpleName())){
                        return clazz;
                    }
                }
            }
        }
        return null;
    }
}
